Skip to Content

the tubes

Posted under Other Technology at .
Tags:hardware, artwork, tube

tubes out for cleaning

Some tubes from a newly arrived vintage radio, out for cleaning . . . for about the first time since it was manufactured. Aren’t they shiny? The story with these is the strange and wonderful alliance of thermionic valve technology and the Internet.

This set is a little over fifty years old. (And I suspect there are people out there who could identify it from the tubes alone.) One of the same model used to live in my parents’ house, humming away happily for nearly twenty-five years, until one day in the late eighties they said it had stopped working and would I look at it.

I had no real experience of working with valves; knew what they were, and loosely what sort of thing they did, but that was all. I opened the back anyway, and noticed that one (now I can tell it was one of the ECL86s) wasn’t properly seated — it was out of its socket, even though it had a wire retaining clip. I pushed it back in and switched on. There was a little explosion, and I switched off. The explosion had pushed the valve back out. It showed no actual signs of damage — it was no different to the other one; so I repeated the exercise, with the same result.

Drama aside, this represented a puzzle. I wondered if somehow the socket was designed to automatically eject a failing valve; interesting concept, but it seemed unlikely. Concluding that it was probably in a dangerous or at least inexplicable state, and since the nearest valve radio repair shop by then was certainly over a hundred miles away, I reported that I could do nothing. With regrets, the radio was dumped, and the house became a valveless zone, albeit one with slightly more shelf space.

This was still a couple of years Ante-WWW. Seemingly, no-one made valves any more. If there was a secondhand market it was a long way away. And critically, no information available, unless you knew which magazines to buy, which books to get through the library, and were prepared to go through months of trying. And replacements? For most people who weren’t obsessive enthusiasts already in the know — forget it. Even the type of cleaning products I use habitually now for electronics were out of reach. This wasn’t the fault of the obsessive enthusiasts though. They were spreading their knowledge in the only ways available.

Valve Protest
(Resistors to Transistors is an evening class, of course . . . )

Over the next few years the Cold War ended, and the Internet spread, and some curious phenomena emerged. One day I read that since valve tech had remained in greater use in the Soviet Union and China, imported replacements might now be obtainable; we could probably order them online. Too late. And information started appearing on what the different valves were and what to do with them, visible on demand, on your very own monitor. In the dying days of CRT displays, all the other tubes returned to life, rescued in large part by t3h intertubes. But still too late.

So internetworking allows better recycling and reuse than has ever previously been possible. I wouldn’t have predicted that. I clearly didn’t. Had we hung on to the radio, even just to look at, the day would have come, probably about ten years ago, when I could have fixed it.

Information access now being easy, and obsessive enthusiasm more liberated than ever, I can say that these are: ECC85 (double triode), EF89 (VHF variable-μ pentode), 2×EF80 (high-slope RF pentode), EB91 (double signal diode), 2×ECL86 (triode-plus-output pentode), EM84 (magic eye). Most of my experience of valves has been in guitar amps, so some of this is outside my range. But there’s a prospect that I might be able to learn what all the radio-specific terminology means, one day. All thanks to the Net.

I haven’t found a mention of other valves blowing out of their sockets — though I do slightly wonder what else the retaining clips were for. I have learned that, chances are, the old tube was fine, but that the socket itself needed cleaning. The explosions, as far as I can work out, were probably high-voltage arcing in a moist accumulation of grime. Or perhaps not, but it would have been worth trying. (Conversely — to date, every device I’ve dealt with which has experienced semiconductor explosions has been clearly terminal.)

Mullard EM84 magic eye

But anyway, a third emergent phenomenon has been the broadening of the secondhand market. Anywhere internet access and postal services extend (subject to seller’s willingness to pack and send), you can now buy old radios at not much more (in real terms) than my parents paid for theirs secondhand in the mid-60s. So finally I’ve done something about it, and they have their radio back. Once properly cleaned and checked over (as far as possible without a tube tester), it creates no explosions, and has a much better sound than the digital TV they’ve defaulted to in recent years. It has a magic eye, it sings sweetly, and really, they weren’t using that shelfspace for anything important.

So thank you, Tim. And the valve anoraks, and everyone else who made the Net what it could be. Now — shall we try to keep it that way?

Comment or Question about this page? write

Article text ©2015 Electropict Creative Commons License.
Click images for individual licences.

next post: achievement changes you
older post: MagSafe As It Should Have Been